Grades and being a URM were two of the factors for our Law Review (one was discussed above, one you can't exactly change). Other than that, a lot of our points depended on how well you could Bluebook (legal citations). So with that in mind, pay attention to the exercises and general guiding tips given to you about citations throughout your first year. If you don't realize how important it is at the time, it's easy to dismiss these lessons.
But every school has different qualifications and will require different things for Law Review. For some schools, anyone can write on with an essay. For others, only a certain percentage of students can. I imagine that if you browse your law school website, you can find out what these qualifications are.